Selective dispersion of semiconducting single-walled carbon nanotubes with arorndtic polyimides

Individually dispersed single-walled carbon nanotubes (SWNTs) with the conductivity of metals or semiconductors only are crucial for their applications in electronics, optics and magnetism. In this work, five aromatic polyimides with varying backbones were initially applied to the study on the dispersion of arc-discharge SWNTs. Spectroscopic characterizations by vis-NIR absorption and Raman scattering confirm that the polyimide molecules possess various selective dispersing ability toward semiconducting SWNTs. The effective dispersion of SWNTs is a result of the spirally wound polyimides around SWNTs dictated by the pi-pi stacking interactions between the backbone of polyimides and the surface of SWNTs, and the selectivity in semiconducting SWNTs is attributable to the charge transfer from polyimide molecules to SWNTs. The various dispersing behaviors of the polyimides toward SWNTs could be accounted for by the difference in aromatic surface area and flexibility of their backbones.